High power microwave switch



Dec. 31, 1968 c. c. JONES HIGH POWER MICROWAVE' SWITCH Filed 001'.. 5, 1965 (no-tg con/'lamme MATRIX DIVIDING MATRIX DRIVE De.31,196s

Filed Oct. 5, 1965 PHASE DIAGRANI OF SIGNAL COMPONENTS COMBINER MATRIX C. C. JONES HIGH POWER MICROWAVE SWITCH RESULTING COMPONENTS FIG. 8.

@GDCDQ DIVIOER M ATRng Sheet 5 I'i I POWER COMBINER MATRIX VARIABLE PHASE SHIFTERS United States Patent O 3,419,821 HIGH POWER MICROWAVE SWITCH l Calvin C. Jones, Jessup, Md., assignor to Westinghouse Electric Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Filed Oct. 5, 1965, Ser. No. 493,088 8 Claims. (Cl. 333-7) ABSTRACT OF THE DISCLOSURE A high power microwave multi-channel switch wherein two hybrid microwave power networks are connected back to back by two-condition phase Shifters which phase Shifters, by being either zero de-gree or 180, can select which output port the input power will exit. Each microwave power network includes first and second sets of three db hybrid couplers connecting alternate and intermediate pairs of channels respectively. In high power applications the inventions simplicity and ability to switch high power with medium power phase Shifters is economically attractive.

The present invention relates generally to high power microwave switches and. more particularly relates to apparatus for multiple-terminal switching of very high microwave power levels using available medium-power components.

It is highly desirable to switch very high RF power levels from one channel to another for the purpose of controlling, for example, multiplebeam array antennas or systems. Unfortunately, in the present state of the microwave switch art there is no available component capable of switching the very high power levels which waveguides are capable of handling.

An object of the present invention is to provide a high power microwave switch capable of handling high microwave power using available medium power components.

Another object of the present invention is to provide a high power microwave switch in which the controlling element requires only two conditions to accomplishthe required switching.

Another object of the present invention is to provide a high power microwave switch of N inputs and N outputs utilizing active elements, each of which need have a capacity only l/N of the input power.

Another object of the present invention is to provide a power switch for any level of power utilizing only one coupler value, say 3 db, and a two state active element.

A more specific object of the present invention is to provide a single pole four throw high power microwave switch requiring only three controlling elements.

These and other objects and advantages of the present invention are accomplished by providing a multiple channel hybrid network switch which uses a power dividing network to split the input power at any particular input into lower power components and shifting the phase of `these power levels before recombining in a combining network which directs the high power output to a chosen output port. More specifically, power introduced into any one of the input ports of the power divider network is divided equally among its output ports. Digital phase Shifters, which need provide only two conditions, selectively delay the phase of the power appearing at chosen output ports and direct such phase shifted power to input terminals of a power combiner network which will emit a recombined power signal from one of its chosen output terminals in accordance with the combination of digital phase shifts determined by the digital phase Shifters. Each network is similarly constructed but connected back-toice back in the high power microwave switch. The duplicate networks provide a cost advantage.

Further objects and advantages of the present invention will be readily apparent from the following detailed de* scription taken in conjunction with the drawing in which:

FIGURE 1 is a phaser diagram useful in understanding the present invention;

FIG. 2 is a symbolic representation of the type of short slot hybrid coupler utilized by the present invention;

FIG. 3 is a schematic diagram of an illustrative embodiment of the present invention;

FIG. 4 is an isometric showing of a mechanical irnplementation of the embodiment schematically illustrated in FIG. 3;

FIG. 5 is an isometric showing of a matrix useful in implementing a further extension of the embodiment of FIG. 3;

FIG. 6 is a schematic diagram of another illustrative embodiment of the present invention; and,

FIGS. 7 and 8 are phase analysis diagrams for selected operations of the illustrative embodiment shown in FIG. 6.

A signal fed into one of the input ports or input terminals of a symmetrical short-slot hybrid coupler results in output signals which differ in phase by Referring to FIGS. l and 2, a signal E1 into the input terminal 1 of a 3 db hybrid coupler symbolically represented by FIGURE 2, is split into two equal amplitude components at the two opposite output terminals 3 and 4, with no coupling to the adjacent input terminal 2. The outputs E3 and E., are equal in amplitude but differ in phase by 90. The phase relationship is shown in the form of the phaser diagram of FIG. 1. The component at the primary output terminal 3 experiences a 45 delay relative to the phase of a signal E0 which would exist at that output terminal if there were zero coupling to the auxiliary or secondary line. The other component E4 experiences a delay which differs by 90 from the primary output E3. In other words, a signal which goes straight through the hybrid coupler comes out with a 45 delay, while a signal which goes across the coupler comes out with a 135 delay. It is assumed that all coupler matrix paths are made of equal electrical lengths, and therefore the above coupler path delays are the only significant phase effects. For simplicity when referring to operational tables to be presented hereinafter, the notation -l-l is hereinafter referred to as a lag of 45 and -1 is a lead of 45 with regard to the relationship between the primary or end. line output component E3 and the secondary or auxiliary output E4.

A high power microwave switch utilizing waveguide hybrid circuits in accordance with the present invention is illustrated in FIG. 3. The switch divides a high power input into a number of lower power parts, then phase shifts these lower power components to cause them to recombine into any one of a multiple output channel array. The number of channels is any binary number, N=2n power, and the total power `which can be switched is equal to N times the power handling capability of the phasing components used. A simple ffour channel switch configuration will be initially presented.

A power dividing network 10 includes the four channels or waveguides 11, 12, 13 and 14 each having an input terminal 1, 2, 3, 4, and an output terminal A, B, C. D, respectively. A first set of hybrid couplers 15 connects alternate pairs of the waveguides; namely, channel :1,1 to 12 and channel 13 to channel 14. A second set of hybrid couplers 16 is located on the output side of 'the frst set 15 of hybrid couplers and connects the intermediate pairs of waveguides; namely, waveguide 2 to waveguide 3, and ywaveguide 4 to waveguide 1. The net- 3 work 10 has been laid out with channels 11 and 14 additionally shown by dotted lines to indicate their proximity to the axial waveguides 14 and 11 respectively. A hybrid coupler connects waveguide 14 to waveguide 11 in the second set I16 of hybrid couplers. The hybrid coupler has one side shown in dotted lines to indicate that only one hybrid coupler connects channel `11 to channel Microwave power introduced into any one of the input terminals of the matrix 10` will be divided equally among the output terminals, A, B, C and D. For the four channel network illustrated the amplitude of the Ipower appearing at any one of the output terminals will be one-quarter the magnitude of the input power appearing at the selected one of the input terminals. The equally divided power components will have different phase relationships as determined by the hybrid couplers interconnecting a-ll four channels.

A power combining network 20 having an equal number of channels 21, 22, 23 and 24 is similarly cross connected as the power dividing network 10 with a third set 25 of hybrid couplers connecting similar alternate pairs o-f waveguides and a fourth set 26 of hybrid couplers located on the input side of the third set 25 of hybrid couplers connects similar intermediate pairs of waveguides. It is an important feature of the present invention that both networks are of similar construction. They are connected back-to-back in the high power microwave switch configuration. Since the networks are connected back-to-baek it is to be noted that the output terminals A, B, C, D, of the power dividing network 10 are utilized in the power combining network 20 as input terminals. Hence, the input terminals of the Waveguides 21, 22, 23 and 24 have been referred to as A', B', C land D', respectively. Further, the input terminals of the power dividing network 10` are now the output terminals of the power combining network 20 and accordingly referred to as 4', 3', 2' and 1. The inversion in location of the output terminals of the network 20 from the input terminals of the network 10 is made since, in the absence of any phase shift, mere connecting of the two networks back-to-back will result in all the power appearing at an input terminal 1 of the network 10 to exit from the output terminal 2' of the network 20. Similarly, power appearing at inputs 2, 3 or 4 will result in the power exiting at output terminals 1', 4', or 3 respectively when no phase shift is inserted between the two networks. In other words, input power into any input terminals 1, 2, 3, or 4 has a corresponding output with high isolation between respective channels being provided by the arrangement.

.In order to direct the power appearing at any one of the input terminals to a `chosen different output terminal, phase Shifters 31, 32, 33 and 34 interconnect the intermediate output terminals A, B, C, and D to respective intermediate input terminals A', B', C', and D'. It is desirable to work from a reference condition of power flow through the microwave switch with such flow being from input terminal 1 to selected output terminals 1', 2', 3', or 4'. By using the representations previously described of +1 and i+1, the following Table I specifics the values of phase shi-ft A, 0B, oC, and :pD to accomplish switching of input 1 into outputs 1', 2', 3'. and 4'.

TABLE I.-INPUT 1 INTO SELECTED OUTPUT TERMINAL II.-INPUT A INTO SELECTED OUTPUT (SIM- PLIFIED TABLE) It can thus be seen from Table II that switchable phase Shifters which are at A, B, C, and D on command can switch an input appearing at terminal 1 to desired output terminal 1', 2', 3', or 4'.

Of interest also are the additional paths provided when inputs 2, 3, and 4 are considered. 4Observe that the initial condition of 0A, 0B, 0C and 0D all equal to zero establishes power appearing at input terminal 1 to exit at output terminal 2'. When input power to terminal 1 is switched to exit output terminal 1' by the addition of (2A-:180 and 0D=l80 column 1 in Table II will become 0, 0, 0, 0 which is the condition for addition into output 1'. Further column 3 becomes 4, 4, 0, 0 which is the condition of addition into output terminal 3 and column 4 becomes 0, 4, 0, 4 which is the condition of addition into output terminal 4'.

By proceeding in similar fashion with input power individually conisdered at each input port, the following composite Table III can be established.

It is to be understood that any suitable microwave phase shifter may be utilized for the Shifters 31, 32, 33 and 34. For example, a ferrite slug may be positioned within a section of waveguide to be energized by a magnetic source either located within or without the containing waveguide. -lt is well known that gy-romagnetic materials, in response to a magnetic field, will shift the phase of microwave energy 'within its waveguide section by an amount determined by the size and configuration of the ferrite slug. Such size and configuration can be selected to provide, upon energization, a phase shift of 180. Since a fixed number of degrees phase shift is desirable it can be seen that digitally operated phase Shifters are preferably utilized.

FIG. 4 illustrates a mechanical implementation of the schematic diagram of FIG. 3 with like items havin-g similar reference characters. The input power enters input terminal 1. Dummy loads terminate the other input terminals 2, 3 and 4. The phase Shifters 30` are of the ferrite toroid type wherein a toroid of chosen length is disposed within each of the interconnecting waveguides and shifts the phase of the microwave energy therethrough upon a pulse of predetermined polarity at the drive lines. A circular magnetic field of predetermined direction is induced in the energized toroid to shift the phase 180.

To demonstrate that the four port switch is indeed typical and extendable to 2n power terminals, an 8 channel matrix for power dividing or power combining is illustrated in FIG. 5. A SPST switch using 8 phase shifters is positioned between a power dividing network, as shown in FIG. 5, and a power combined network, obtained by reversing the network of FIG. to provide an '8 port 6 then enter the combining matrix 50 at: A', B', C' and D' respectively and is further split into four equal amplitude outputs which are of diifering phase. These are represented by four columns of the four output signals shown coupler and across the second. Hence, the component at B experiences 454-135 or 180 total delay. The reremaining components are easily derived in the same way.

Each of the four power components at A, B, C and D high power microwave switch. 5 to the right of output terminals 1', 2', 3', fand 4' in FIG. A 16 port switch has been constructed following the 7. It is to be noted that the power components add up same procedure. Table IV indicates the necessary phase horizontally to a resultant output, which for the illusshift to switch input power at the input terminal 1 to trated case is zero in all but output terminal 1', where all any desired output terminal 1 through l16'. The shifter the power merges if one assumes ideal lossless matrices. table corresponds to Table II for the four pole switch. 10 Using a similar analysis, it is simple to show how in- It can be shown that a pattern of paths is established troducing 180 phase shifts at terminals C and D will similar to that shown in Table IV. -If a single input is cause all the power coming into input terminal 1 to be desired the input divider reduces to couplers and N-l switched to output terminal 2'. FIG. 8 is similar to FIG. 6 or 15 in this case active phase shifter elements a-re reexcept for the introduction of the phase Shifters 51, 52, quired. 15 53 and 54. With the addition of 180 phase shift by phase TABLE IV i' 2' 3' .4 5' 6' 7 s 9' i0l ii' 12' i3' i4 i5' i0' Another illustrative embodiment of the present inven- Shifters 53 and 54 the output components in columns C tion is schematically shown in FIG. 6. Here, the power and D are reversed in direction compared with FIG. 7. divider a network 40, again has four channels 41, 42, 43 45 By adding in a similar manner as in FIG. 7 the comand 44, each having a respective input terminal, 1, 2, 3, plete power combination exits at output terminal 2', with and 4 and a respective inter-mediate output terminal A, zero power output at the other output terminals. B, C, and D. A first set 45 of hybrid couplers connect The values of phase shift required in this simplified alternate pairs of channels or waveguides. A crossover 46 arrangement and the corresponding switch paths estabinterchanges the position of waveguides 42 and 43. A 50 lished, are shown in the following Table V.

second set 47 of hybrid couplers then connect every other waveguide; namely, waveguide 1 to waveguide 3 and TABLE V-"PHAIllaQfl/IVIWCOR A FOUR CHAN waveguide 2 to waveguide 4. A power combiner network Ph Shft V l 50 is similarly constructed for channels 51 52 `53 and 5-4 as@ 1 a les S hPthEtbhhd with their respective output terminals 1', 2', 3', and 4. 55 Wm a s s a s e @A @B C D Digital phase Shifters 5.1 through 54 interconnect the 1 ,122, 23 ,34g ,4, O o 0 0 channels of the power divider network 40 and the power 4 g g 1800 -iso -gr e r a ly l, l o e combmer network 50' i 44",2 -43,34 2',44 i' 180 0 0 -is0 The -flow of power components through the microwave power switch when the divider network and combiner network 40 and 50I are connected back-to-back The foregoing composite table is comparable to the without phase shifters or all phase Shifters set at zero is composite Table III previously derived for the embodishown in FIG. 7. Power is fed into the divider network ment of FIG. 3. 40 at input terminal 1. It splits into four equal amplitude Thus is should be readily apparent that the present components at intermediate terminals A, B, C and D as invention has provided means for the switching of high shown. The component at A is shown with a 90 phase power microwave energy while making use of presently lag with respect to the dotted reference phase. This 90 available phase shifting or switching components. The lag results from the signal at A having gone straight power divider network divides the input microwave enthrough two hybrid couplers, each contributing a 45 ergy into equal components of a magnitude readily delay. The component at B lgoes straight through the lirst switched by available phase shifters. The power combining network then gathers the shifted components and recombines them for exiting at a selected output port. Two configurations of a single pole four throw switch have been illustrated as Well as a 8 channel and 16 channel switch. The number of channels which can be switched is any binary number N :2n power, and the total power which can be switched is equal to N times the power handling capability of the waveguide phase shifter components used. A simple four channel switch configuration has been thoroughly discussed. A four channel switch was chosen to avoid excessive complexity in the discussion but is also a very practical configuration for the many array systems which use 4 planar arrays to achieve hemispheric coverage.

While the present invention has been described with a degree of particularity, for the purposes of illustration, it is to be understood that all modifications, alterations and substitutions within the spirit and scope of the present invention are herein meant to be included. For example, while dominant mode waveguides have been illustrated, it is to be understood that other forms of channels or transmission lines may be utilized.

I claim as my invention:

1. A high power microwave multichannel switch comprising, in combination; a power dividing network and power combining network each including N channels; each channel having an input terminal and an output terminal; said power dividing network including a rst set of 3 db hybrid couplers connecting alternate pairs of channels and a second set of 3 db hybrid couplers connecting intermediate pairs of channels to divide a microwave signal at any of its input terminals into equal amplitude components at all N output terminals; said power combining matrix including a like first set and second set of 3 db hybrid couplers connecting like channels respectively to combine signals at N input terminals into any one output terminals; and means connecting an output terminal of said power dividing network to a respective input terminal of said power combining network for selectively shifting the phase of energy therethrough in 180 steps.

2. The switch of claim 1 wherein said means for selectively shifting includes N digital phase Shifters each connecting an output terminal of said power divider network to an input' terminal of said power combining network, respectively.

3. A multiple channel hybrid matrix switch comprising, in combination; a first and a second network each including a plurality of channels arranged in a circular array and each having an input terminal and an output terminal; a first set of hybrid couplers in said first network connecting alternate pairs of channels; a second set of hybrid couplers in said first network connecting the intermediate pairs of channels and located on the output side of said first set of hybrid couplers; a third set of hybrid couplers in said second network connecting similar intermediate pairs of channels and located on the input side of said third set of hybrid couplers; and means connecting an output terminal of said first network to a respective input terminal of said second network for selectively shifting the phase of energy therethrough in 180 steps.

4. The hybrid matrix switch of claim 3 wherein said couplers are directional with 3 db coupling.

5. A microwave switch comprising in combination; two multiple channel network each including a combination of hybrid couplers interconnecting the channels associated therewith which, for power flow in one direction, divide a signal at any one input port into equal amplitude components at all N output ports while, for power fiow in the opposite direction, combine equal amplitude components at all N output ports, now input ports, into any one input port, now output port; and digital phase shifting means interconnecting back-to-back the output ports of one of said networks to the now input ports of the reversed other of said networks for selectively shifting the phase of energy between selected output ports of said one of said networks and the now input ports of said reversed other of said networks in steps.

6. The microwave switch of claim 5 wherein said couplers are directional with 3 db coupling.

7. A single throw four pole microwave switch comprising, in combination; a power divider network of four channels each including an input port and an output port; rst hybrid coupler means connecting the first channel to the second channel and the third channel to the fourth channel; second hybrid coupler means connecting the third channel to the first channel and the second channel to the fourth channel; crossover means interchanging the physical position of the second channel with the third channel and positioned between the first hybrid coupler means and the second hybrid coupler means; a power combiner network including four channels as well as another first and second hybrid coupler means and crossover means disposed in the same manner in the power combiner network as in the power divider network; a first digital phase shifter connecting the output port of the first channel of the power divider network to the input port of the first channel of the power combiner network, a second phase shifter connecting the output port of the third channel of Said power divider network to the input port of the second channel of the power combiner network; a third phase shifter connecting the output port of the second channel of said power divider network to the input port of the third channel of said power combiner and a fourth phase shifter connecting the output port of the fourth channel of said power divider network to the input port of the fourth channel of said power combiner network; said phase Shifters selectively shifting the phase of microwave power in digital steps of 180.

8. The switch of claim 1 including crossover means between said first set and said second set of 3 db hybrid couplers interconnecting at least one channel of said alternate pairs to one channel of said intermediate pairs.

References Cited UNITED STATES PATENTS 3,058,071 10/1962 Walsh et al. 333-11 3,124,801 3/1964 Callahan 343-854 3,184,691 5/1965 Marcatili et al. 333-11 3,255,450 6/1966 Butler 343-853 XR 3,276,018 9/1966 Butler 343-854 XR OTHER REFERENCES Investigation of a Multiple Beam Scanning Circular Array, Chadwick and Glass Radiation Systems Inc., Alexandria, Va., 1964. Title page, pp. 25-27.

ELI LIEBERMAN, Primary Examiner.

M. NUSSBAUM, Assistant Examiner.

U.S. Cl. X.R. 

